I am looking for software that can alter voice recordings so they can be used without the speaker being recognized by the listeners. Does such a program exist? Up until now I have used command line utilities like ffmpeg and it’s associated filters.
You could try using Audacity. Select your audio recording and then adjust for pitch and speed, for example.
Thank for this suggestion. I ended up writing a small app using ffmpeg and putting a user interface in front of that. I needed to process about 90 files, and so my app does that in bulk. If that sounds interesting to anyone else, you can let me know here and we will get in touch with each other
If all you need is for recordings to not be recognized by other speakers, this all sounds fine. If, on the other hand, you think there is a chance that someone may attempt to reverse this process (like a very high resourced adversary), then another solution might be Ircam Trax v3. It’s quite pricey and not trivial to set up (Use the Flux Center to download and iLOK to set up the license, then it operates as a plugin for Adobe Audition or similar program), but a voice can be manipulated into a different, natural-sounding voice that is virtually impossible to reverse engineer.
Thank you for this suggestion, and your concern for the safety of those with whom we minister. I do not believe that these recordings will bring a broader than local risk to those who made them. The program that I am using (ffmpeg) is quite good, allowing to change pitch, tempo, timber, and vibrato. Thanks again.